The use of composite materials to strengthen masonry structures has become common practice within the civil engineering community. Steel-reinforced grout (SRG), which comprises high-strength steel fibers embedded in a mortar matrix, is part of the family of the fiber-reinforced cementitious matrix (FRCM) composites that represent a suitable alternative to fiber-reinforced polymer (FRP) composites for strengthening existing structures. Although studies on FRCMs have already reached a certain level of maturity, some key issues remain open, such as the role of matrix type and layout, substrate properties, and test rate. This paper focuses on some of these issues. The results of single-lap direct shear tests on masonry blocks strengthened with SRGs are presented to analyze the bond behavior between the composite material and the substrate. Four aspects are considered: (1) the change in the width of the SRG mortar matrix while keeping the width of the fiber sheet fixed; (2) the type of mortar used for the SRG; (3) the influence of the test rate, and (4) the type of substrate (i.e., concrete vs. masonry). The results obtained indicate the active role of the matrix layout and the importance of the test rate, encouraging further investigations to clarify these aspects.

中文翻译：

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SRG和砌体之间的应力传递力学中的一些关键方面

在土木工程界内，使用复合材料来增强砖石结构已成为普遍的做法。包含在砂浆基质中的高强度钢纤维组成的钢筋水泥浆（SRG）是纤维水泥质基质（FRCM）复合材料家族的一部分，代表了纤维增强聚合物（FRP）的合适替代品用于增强现有结构的复合材料。尽管对FRCM的研究已经达到一定的成熟水平，但仍存在一些关键问题，例如基质类型和布局，底物特性和测试速率的作用。本文重点讨论其中的一些问题。提出了用SRGs加固砌体砌块的单圈直接剪切试验的结果，以分析复合材料与基底之间的粘结行为。考虑了四个方面：（1）在保持纤维板宽度固定的同时，改变SRG砂浆基质的宽度。（2）SRG用的砂浆类型；（3）测试率的影响，以及（4）基材的类型（即混凝土与砌体）。获得的结果表明矩阵布局的积极作用和测试率的重要性，鼓励进一步研究以澄清这些方面。